Re-land: base: Fix registering of memory pressure listeners used when emulating discardable memory.

base/memory/discardable_memory_unittest.cc

Index: base/memory/discardable_memory_unittest.cc
diff --git a/base/memory/discardable_memory_unittest.cc b/base/memory/discardable_memory_unittest.cc
index 18704513f13d639f6f176ee83b5ea449b7843c17..d4a230a46fa7c3d2257d17aa156cc90b226ba7cc 100644
--- a/base/memory/discardable_memory_unittest.cc
+++ b/base/memory/discardable_memory_unittest.cc
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(OS_ANDROID)
@@ -17,11 +18,23 @@ namespace {
 
 class DiscardableMemoryTest
     : public testing::TestWithParam<DiscardableMemoryType> {
+ public:
+  DiscardableMemoryTest() : message_loop_(MessageLoop::TYPE_IO) {
+    // Register memory pressure listeners now that we have a message loop.
+    DiscardableMemory::RegisterMemoryPressureListeners();
+  }
+  virtual ~DiscardableMemoryTest() {
+    DiscardableMemory::UnregisterMemoryPressureListeners();
+  }
+
  protected:
   scoped_ptr<DiscardableMemory> CreateLockedMemory(size_t size) {
     return DiscardableMemory::CreateLockedMemoryWithType(
         GetParam(), size).Pass();
   }
+
+ private:
+  MessageLoop message_loop_;
 };
 
 const size_t kSize = 1024;